Excitation system



April 11, 1939. H, A E 2,154,284

EXC ITAT ION SYSTEM Filed April 24, 1937 4 Sheets-Sheet l WITNESSES: I INVENTOR W Herberf z? Pose.

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ATTORN EY April 11, 1939. E 2,154,284

EXCITATION SYS TEM Filed April 24, 1937 4 Sheets-Sheet 2 Fig. 2.

Graphile WITNESSES: INVENTOR W 6M Herberf/Z Pose.

ATTORNEY April 11, 1939. H. A. ROSE I 2,154,284

EXCITATION SYSTEM Filed April 24, 1957 4 Sheets-Sheet 3 wnussszs: lNvENToR WW HerberffiFose,

ATTORN EY April 11, 1939.

H. A. ROSE 2,154,284

EXCITATION SYSTEM Filed April 24, 1937 4 Sheets-Sheet 4 WITNESSES:

Grip/vi e mvamor I Herberz fl Q05 6,

[ex A l'ToRNEY Patented Apr. 11, 1939 UNITED STATES PATENT OFFICE EXCITATION SYSTEM vania Application April 24, 1937, Serial No. 138,819

20 Claims.

My invention relates to an excitation system for a vapor electric device, and particularly to an excitation system having a static starting means.

In the operation of vapor electric converters, such as rectifiers, it has been customary to use an excitation electrode supplied with current from a suitable auxiliary source and to draw the are from this exciting electrode to the cathode of the device by means of. suitable mechanism which establishes contact between the exciting electrode and the cathode and then breaks this connection to initiate a keep-alive arc. This use of a mechanically moving part in an otherwise static device is highly unsatisfactory as the repeated operations may injure or even destroy the starting mechanism where the remainder of the device is in satisfactory working condition. There has recently been discovered a new starting principle wherein a current is passed through a body of resistance material in contact with the cathode to initiate a cathode spot at the beginning of any conducting period.

It is an object of my invention to provide an excitation system in which a keep-alive electrode has connected in series therewith a suitable resistance body or make-alive electrode, and to provide a source of excitation potential which will apply at the moment of starting a sufficiently high potential to initiate a cathode spot after which the excitation arc continues to burn through'the keep-alive electrode at a somewhat reduced potential, preferably at a potential which produces a relatively unimportant current through the make-alive electrode.

It is a further object of my invention to provide an excitation system having an auxiliary source of keep-alive potential provided by the operation of the converter itself such as a potential derived from the harmonics generated in the converter or a potential derived from a stabilizing device such as an interphase transformer.

It is a further object of my invention to provide an excitation system using normally waste or dissipated energy to provide the excitation current.

Other objects and advantages of my invention will be apparent from the following detailed description, taken in conjunction with the accompanying drawings, in which:

Figure 1 is a schematic illustration of a conversion system utilizing my excitation system.

Fig. 2 is a similar view showing a modification according to my invention.

Figs. 3 and 4 are similar views showing the method of utilizing excitation currents from the operating values of the converter; and,

Fig. 5 is a diagrammatic illustration of the voltages and currents applied to the excitation 5 electrodes.

In the illustrative embodiment of my invention according to Fig. 1, a vapor electric device such as a multi-anode rectifier l feeding a direct current circuit 2 is supplied from an alterlo nating current circuit 3 by means of a suitable transformer arrangement 4 herein illustrated as double three-phase with interphase, although any suitable transforming device may be utilized.

In the converter l is provided a suitable excita- 15 tion electrode 5 spaced from the cathode 6 of the device I and having mechanically connected thereto and extending into contact with the cathode a suitable body 1 of resistance material suitable for forming a make-alive electrode. While any suitable material may be used for this resistance body, I have found that carborundum crystals, or a formed body of boron and carbon in the nature of boron carbide are particularly useful. A suitable source of excitation current is provided herein illustrated as an excitation transformer 8 deriving energy from the alternating current circuit 3, either directly or through a suitable operating transformer 9. The output potential of the excitation transformer 8 is rectified by a suitable rectifying device l0 and connected between the excitation electrode 5 and the cathode B of the device I. Preferably, the excitation circuit is provided with a current limiting resistor H and a stabilizing reactor l2 in order to control and limit the exciting current.

In the operation of the system according to my invention, the exciting transformer 8 is en ergized and the resultant potential rectified by 40 the rectifying device I0 when applied to the exciting electrode 5 and the cathode 6 of the device I, so that the rectified potential appears across the make-alive electrode 1, the exciting transformer 8 having a sufficiently high potential to 45 cause suflicient current flow through the makealive electrode I to initiate a cathode spot on the cathode 6 of. the device I after which a keepalive arc will be struck from the exciting electrode 5 to the cathode 6 of the device. Preferably, the excitation transformer 8 is provided with a high regulation characteristic so that after the excitation arc has begun to burn, the terminal voltage will be reduced to a level sufficient to maintain the keep-alive are but at a value which does not produce objectionable currents in the make-alive electrode 1.

If desired, the keep-alive electrode is divided into two parts, one portion H! of the keep-alive electrode being in the vicinity of the anodes 15 to be excited. Preferably a resistor [G of suitable value is connected between these keep-alive electrodes 5 and i4 so that after the device has become excited, the major portion of the keepalive arc will transfer to the exciting electrode l4 adjacent the anodes 15.

In the modification according to Fig. 2 I have provided a plurality of similar excitation electrodes 5, preferably each being provided with a suitable make-alive electrode 7 and apply the output potential of the excitation transformer 8 directly to the keep-alive electrodes 5 without the necessity of an intervening rectifying device. The operation of this form of the invention is substantially identical with that described above except that the keep-alive arc transfers between the excitation electrodes 5 with the alternations of the potential supplied by the excitation transformer 8.

In the modification according to Fig. 3, an initial keep-alive arc is struck in the manner shown in Fig. l as described above. However, a plurality of auxiliary exciting electrodes 25 are provided, preferably each of these auxiliary electrodes 25 being also provided with a suitable make-alive electrode 1. These auxiliary electrodes 25 are supplied with potential from a transformer 26 energized at a frequency which is a harmonic of the frequency supplied to the main anodes l5 of the device I and being derived from a circuit 21 connected across the direct current circuit 2 fed by the converter i. This circuit comprises a suitable capacitor 28 and a reactor 29 forming the primary of the auxiliary excitation transformer 26. While suitable operation may be obtained with an untuned circuit, it is frequently found desirable to tune this-auxiliary circuit 27 to a suitable harmonic generated by the converter I. Preferably this auxiliary excitation source is connected ahead of the usual telephone filter circuits which generally include a series reactor 3| in the direct current circuit 2 and suitable shunt filters 32 across the circuit 2. I prefer to provide the initial keep-alive circuit with a suitable contacting device 33 which will be operative to disconnect the initial keepalive circuit when the current through the converter I is suflicient to provide the necessary excitation current from the auxiliary source 36.

In the embodiment of my invention according to Fig. 4, the auxiliary electrodes 25 are connected to an auxiliary winding 35 on the interphase transformer 35 which is excited by the exciting current of the interphase transformer. Preferably the control device 33 for deenergizing the primary exciting circuit is so regulated that this primary circuit will not be interrupted until after sufficient current flows to excite the interphase transformer 3! so as to eliminate any danger of the primary circuit being interrupted before the actual operation of the auxiliary keepalive circuit 35 and to insure that the primary circuit will be again connected before termination of the flow of exciting current from the auxiliary source 35.

According to the diagrammatic illustration in Fig. 5, it is seen that the exciting transformer 8 has a step regulation characteristic so that prior to current flow in the exciting electrodes 5, a sufiiciently high potential 46 will be supplied to the make-alive electrodes 1 to insure their operation to create a cathode spot. However, when current begins to flow in the keep-alive electrode the voltage decreases as shown by the curve 4| to a point 42 sufficient to maintain the keepalive are but insufficient to provide operating current for the make-alive electrode 1. After the main arcs of the converter are established, the strong ionization in the device 1 permits an in crease of current in the keep-alive are which further reduces the potential supplied by the excitation transformer as shown at 43.

While for purposes of illustration I have shown and described specific embodiments of my invention, it will be apparent to those skilled in the art that many changes and modifications can be made therein without departing from the true spirit of my invention and the scope of the appended claims.

I claim as my invention:

1. An electric current converting system comprising an alternating current supply circuit, a vapor-electric device having a plurality of anodes and a vaporizable cathode, transformer means for supplying potential from said alternating current circuit to said anodes, a direct current circuit connected to said device, a keep-alive electrode in said device, a body of material suitable for operation as a make-alive electrode electrically connected to said keep-alive electrode and extending between said keep-alive electrode and the cathode of said device, a source of keep-alive potential and connections for impressing said potential between said keep-alive electrode and said cathode.

2. An electric current converting system comprising an alternating current supply circuit, a vapor electric device having a plurality of anodes and a vaporizable cathode, transformer means for supplying a potential from said alternating current circuit to said anodes, a direct current circuit connected to said device, a keep-alive electrode in said device, a body of material suitable for operation as a make-alive electrode extending between said keep-alive electrode and the cathode of said device said body being electrically connected to said keep-alive electrode, an auxiliary source of alternating current, means for rectifying current from said source and connections for impressing said rectified current between said keep-alive electrode and the cathode of said device.

3. An electric current converting system comprising an alternating current supply line, a vapor electric device of the arcing type having a plurality of anodes and a vaporizing cathode, transformer means for supplying potential to the anodes from said supply line, a direct current cireuit supplied by said device, an excitation electrode in said device, said electrode being spaced from said cathode, a body of resistance material electrically connected to said electrode and ex tending into contact with said cathode and means for supplying exciting current between said electrode and said cathode.

4. An electric current converting system comprising an alternating current supply line, a vapor electric device of the arcing type having a plurality of anodes and a vaporizing cathode, transformer means for supplying potential to the anodes from said supply line, a direct current circuit supplied by said device, an excitation electrode in said device, said electrode being spaced from said cathode, a body of resistance material electrically connected to said electrode and extending into contact with said cathode and means for supplying exciting current between said electrode and said cathode, said resistance body having a resistance such that the potential necessary to maintain an are between said exciting electrode and said cathode will produce only a relatively small current in said resistance body.

5. An electrical conversion system comprising an alternating current circuit, a direct current circuit, a vapor electric device including a plurality of anodes and a vaporizable cathode, transformer means including an interphase transformer for supplying current to said device, an exciting electrode in said device, a source of exciting current connected to said electrode, means for initiating an exciting are between said electrode and the cathode, a plurality of auxiliary exciting electrodes in said device, an auxiliary winding on said interphase transformer and means for connecting said auxiliary winding to said auxiliary electrodes.

6. An electrical conversion system comprising an alternating current circuit, a direct current circuit, a vapor electric device including a plurality of anodes and a vaporizable cathode, transformer means including an interphase transformer for supplying current to said device, an exciting electrode in said device, a source of exciting current connected to said electrode, a make-alive electrode electrically connected to said electrode and extending into contact with the cathode for initiating an exciting are between said electrode and the cathode, a plurality of auxiliary exciting electrodes in said device, an auxiliary winding on said interphase transformer and means for connecting said auxiliary winding to said auxiliary electrodes.

'7. An electric current conversion system comprising two dissimilar electrical circuits, a multivalve vapor electric converter for transferring energy between said circuits, an exciting electrode in said converter, a rod of high resistance material extending between said exciting electrode and the cathode of said converter said rod being electrically connected to said exciting electrode and means for impressing an exciting potential between said exciting electrode and the cathode of said converter.

8. An electric current conversion system comprising two dissimilar electrical circuits, a multivalve vapor electric converter for transferring energy between said circuit, an exciting electrode in said converter, a rod of high resistance material extending between said exciting electrode and the cathode of said converter, said rod being electrically connected to said exciting electrode, means for impressing an exciting potential between said exciting electrode and the cathode of said converter, an auxiliary exciting electrode in said converter and means for transferring a major portion of the exciting current from said first mentioned exciting electrode and said auxiliary exciting electrode.

9. An electrical translating system for transferring electrical energy between two dissimilar electrical circuits, one of which is an alternating current circuit comprising an arc type converter including a plurality of main electrodes one of which is a vaporizable cathode, transformer means for connecting said converter to said circuits, a keep-alive electrode in said converter, a source of exciting current connected to said keepalive electrode and said cathode, make-alive means for initiating the flow of exciting current in said device, a plurality of auxiliary keep-alive electrodes in said converter, a second source of exciting current energized by current flow in said converter and means for connecting said second source of current to said auxiliary keep-alive electrodes.

10. An electrical translating system for transferring electrical energy between two dissimilar electrical circuits, one of which is an alternating current circuit comprising an arc type converter including a plurality of main electrodes one of which is a vaporizable cathode, transformer means for connecting said converter to said circuits, a keep-alive electrode in said converter, a source of exciting current connected to said keepalive electrode and said cathode, make-alive means for initiating the flow of exciting current in said device, a plurality of auxiliary keep-alive electrodes in said converter, a second source of exciting current energized by current flow in said converter, means for connecting said second source of current to said auxiliary keep-alive electrodes and means responsive to current flow to said auxiliary keep-alive electrodes to inhibit current flow to said first-mentioned keep-alive electrode.

11. An electric current conversion system comprising two dissimilar electrical circuits, a vapor electric device having a plurality of anodes and a cathode of vaporizable reconstructing material therein, transformer means for coupling said device to said circuits, an exciting electrode in said converter, a body of resistance material' secured to said exciting electrode and extending into said cathode, said body having a resistance such that the potential necessary to produce an appreciable current therethrough is materially higher than the potential necessary to maintain an are between said exciting electrode and said cathode and means for impressing an exciting potential between said exciting electrode and said cathode.

12. In combination with a vapor-electric device fed by transformer means including an interphase transformer, an excitation system comprising an exciting electrode in said device, a source of exciting current connected to said electrode, a make-alive electrode electrically connected to said electrode and extending into contact with the cathode of said device for initiating an exciting arc, auxiliary exciting electrodes in said device, an auxiliary winding on said interphase transformer and means for connecting said auxiliary winding to said auxiliary electrodes.

13. In combination with a vapor-electric device fed by transformer means including an interphase transformer, an excitation system comprising an exciting electrode in said device, a source of exciting current connected to said electrode, a make-alive electrode electrically connected to said electrode and extending into contact with the cathode of said device for initiating an exciting arc, auxiliary exciting electrodes in said device, an auxiliary winding on said interphase transformer and means for con.- necting said auxiliary Winding to said auxiliary electrodes, and make-alive electrodes connected to each of said auxiliary electrodes and extending into contact with the cathode of said device.

14. In combination with an electric current conversion system comprising a plurality of dissimilar electrical circuits, a vapor electric converter including a plurality of anodes and a vaporizable cathode for controlling current flow between said circuits, an exciting system comprising an exciting electrode spaced from said cathode, a body of high resistance material electrically connected to the exciting electrode, said body extending between said exciting electrode and said cathode, means for impressing exciting potential on said exciting electrode, a plurality f auxiliary exciting electrodes, a high resistance body extending from each of said auxiliary electrodes into contact wth said cathode, a source of alternating current exciting potential and means for impressing said alternating current exciting potential on said auxiliary electrodes.

15. In combination with an electric current conversion system comprising a plurality of dissimilar elcctrical circuits, a vapor electric converter including a plurality of anodes and a vaporizable cathode for controlling current flow between said circuits, an exciting system comprising an exciting electrode spaced from said cathode, a body of high resistance material electrically connected to the exciting electrode, said body extending between said exciting electrode and said cathode, means for impressing exciting potential on said exciting electrode, a plurality of auxiliary exciting electrodes, a high resistance body extending from each of said auxiliary electrodes into contact with said cathode, a source of alternating current exciting potential and means for impressing said alternating current exciting potential on said aux liary electrodes, said source of alternating current excitation being derived from a capacitor and a reactor connected to one of said electrical circuits.

16. An excitation system for a vapor electric device having a vaporizable cathode comprising an excitation electrode spaced from the cathode of the device, a body of high resistance material electrically connected to said excitation electrode and extending into permanent contact with the cathode. a source of exciting current and connections from said source to said electrode and said cathode.

17. An excitation system for a vapor electric device having a vaporizable cathode comprising an excitation electrode spaced from the cathode of the device, a body of high resistance material electrically connected to said excitation electrode and extending into permanent contact with the cathode, a source of exciting current and connections from said source to said electrode and said cathode, a second keep-alive electrode in said device and means in series with said excitation electrode for transferring the major portion of the exciting are from said exciting electrode to said keep-alive electrode.

18. An electric current conversion system comprising an alternating current circuit, a direct current circuit, a vapor-electric device having a plurality of anodes and a vaporizable reconstructing cathode for controlling current flow between said circuits, an exciting electrode in said device, a body of material suitable for makealive electrodes electrically connected to said exciting electrode and extending between said exciting electrode and the cathode of said device, means for impressing exciting potential on said exciting electrode, a plurality of auxiliary exciting electrodes in said device, a source of alternating current exciting potential and means for impressing said alternating current exciting potential on said auxiliary electrodes.

19. An electric current conversion system comprising an alternating current circuit, a direct current circuit, a vapor-electric device having a plurality of anodes and a vaporizable reconstructing cathode for controlling current flow between said circuits, an exciting electrode in said device, a body of material suitable for makealive electrodes extending between said exciting electrode and the cathode of said device, said body being electrically connected to said exciting electrode, means for impressing exciting potential on said exciting electrode, a plurality of auxiliary exciting electrodes in said device, a source of alternating current exciting potential and means for impressing said alternating current exciting potential on said auxiliary electrodes, and means responsive to flow of exciting current to said auxiliary electrodes for interrupting curren flow in said first-mentioned exciting electrode.

20. An electric current converting system comprising an alternating current circuit, a direct current circuit, a vapor-electric device having a plurality of anodes and a vaporizable cathode, transformer means connecting said circuits to said vapor-electric device, a keep-alive electrode in said device, a body of material suitable for operation as a make-alive electrode electrically connected to said keep-alive electrode and extending between said keep-alive electrode and the cathode of said device, a source of exciting potential, connections for impressing said potential between said keep-alive electrode and said cathode, a second reep-alive electrode in said vapor-electric device, a second source of exciting potential including a capacitor and a reactor connected in series across said direct current circuit and means for connecting said second source of exciting current to said second mentioned keep-alive electrode.

HERBERT A. ROSE. 

